Signaling system for telephone-exchanges.



No. 849 336. PATENTED APR. 2, 1907.

y P. R. McBERTY. SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

APPLICATION FILED JAN.20.1905.

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PATENTED APR. 2, 1907.

F. R. MoBBRTY; SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

APPLICATION FILED JAN. 20. 1905.

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V UNITED snares PATEN T OFFICE.

FRANK R. McBERTY, OF EVANSTON, ILLINOIS, ASSIGNOR TO WESTERN ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLI- NOIS.

SIGNALING SYSTEM FOR TELEPHONE-EXCHANGES.

Specification of Letters Patent.

Patented April 2, 1907.

Original application filed July 11,1902, Serial No. 115,131. Divided andthis application filed January 20,1905. Serial No. 241,962.

To aZZ whom it may concern:

Be it known that I, FRANK R. MoBnR'rY, a citizen of the United States,residing at Evanston, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Signaling Systems forTelephone-Exchanges, of which the following is a full, clear, concise,and exact description.

My invention relates to a signaling system for telephone-exchanges, andhas for its object to provide an improved and simple arrangement ofcircuits and apparatus to be associated with the telephonelines forcontrol- I 5 ling the operation of the visible signals adapted toindicate to the central-oflice operator calls for connection anddisconnection.

My invention contemplates a number of telephone-lines each provided atthe central office with a ground branch from one line conductorincluding a magnet adapted when energized to effect the display of avisual callsignal. A branch at the central ollice leads to earth fromthe other line conductor, and

the substation telephone-switch is adapted when closed to unite saidline conductors and complete a circuit for said magnet, including asource of current. A connection-switch is provided at the centralo'l'lice adapted when closed to unite the link conductors of theoperators cord-circuit with the telephone-line and apply current theretofrom a battery associated with the link conductors, which effects theenergization of a magnet adapted to 3 5 withdraw said visual signal.

The operator is provided with a supervisory visual signal or signalsassociated with the link conductors of her cord-circuit, having anindicator-displaying magnet, which upon the closure of theconnection-switch to unite the link conductors with a telephoneline isincluded in a circuit with a source of current independent of thetelephone-switch of such line, while the indicator-restoring magnet ofsuch signal is included upon the closure of said connection-switch in acircuit controlled by said substation telephoneswitch. It will thus beseen that upon the closure of the connection-switch the line-sig- 5 nalis Withdrawn and the supervisory signal brought under the control of thetelephoneswitch.

I will describe my invention more particularly by reference to theaccompanying drawings, wherein Figure 1 is a dia ram of atelephone-exchange system embodying my invention. Fig. 2 is a sideelevation of the visual-signal device which I prefer to employ. Fig. 3is a plan view thereof. Fig. 4 is a front elevation of the signal withthe indicator c011- cealed, and Fig. 5 is a rear view thereof.

The telephone-line shown in the drawings extends in two limbs 1 2 from asubstation A to the line-springs and test-thimbles a a respectively, ofmultiple spring-jacks a at the central oliice. A branch conductor 3leads .from the limb 1 between the spring-jacks and the substation toearth through the magnet I) of the electromagnetic signal device 1) andcentral-ol'lice battery B, while a branch 4 ex tends to earth throughthe armature c and its back contact 0 of a magnet c, forming part ofsaid signal device.

The magnet b is adapted when energized upon the closure of thesubstation telephoneswitch to effect the display of a visual indicator(Z, which in the device shown is carried by a lever I)", normallyoverbalanced by the armature b of said magnet I), so as to maintain theindicator concealed. Said magnet c is adapted upon its energization toeffect the concealment of the indicator (Z and open the ground branch4,1eading from the conductor 2, the said armature c engaging theindicator and moving it back to its normal concealed position. Themagnet c is included in conductor 1 between the ground branch includingthe indicator-displaying magnet and the spring-jacks and may be shuntedby the usual non-inductive resistance.

The apparatus and circuits of the tele phone-line from station C areprecisely identical with those just described.

The operator is provided. with a pair of link conductors 5 6,terminating in tip and ring contacts a e and c 6 respectively, ofanswering and calling plugs c c, each of the con ductors including theusual condenser f. The plugs and spring-jacks together constituteconnection-switches adapted when closed to unite the operatorscord-circuit with the two telephone-lines. A grounded battery B isassociated with the link conductors, its grounded pole being connectedby a conductor 7, including the in(licator-displaying magnet b of anelectromagnetic supervisory-signal device g similar to the line-signal,with the tip-strand 5 of the cord-circuit, while the free pole of saidbattery is connected by a conductor 8, including the restoring-magnet cof the said signal device, with the ring-strand 6. The windings of bothmagnets of the supervisory signal may be of one hundred ohms, butSllOllld have high impedance. In a like manner conductors 7 8 lead fromthe poles of the battery B through the magnets b c of the supervisorysignal 7b to the tip and ring strands 5 6, respectively, the condensersf being interposed between the points where the conductors 7 7 a and 88, associated with the plugs e e, join their respective link conductors.

It will be understood that the operator is rovided with the usuallistening and ringing {6Y5 for connecting her telephone set with thecord-circuit and for applying ringing-current to the called line. W hilel have shown three batteries in the drawings, it will be understood, ofcourse, that in practice these may be and usually are one and the samebattery.

Referring now to Figs. 2 to 5, I will clescribe the mechanism of thevisual signal which I prefer to employ in carrying out my invention. Thearmature b of the indicatordisplaying magnet b is pivoted beneath itscenter of gravity, so that the armature tends to fall away from themagnet, and in this position is adapted to engage the short end of apivoted lever b carrying the indicator (Z to normally maintain the sameconcealed. The indicator-arm is nearly balanced bya small weight at itsrear extremity; but the indicator is of such weight that it tends topass to its lower position upon the attraction of the armature b. Thearmature c of the restoringmagnet c is pivoted above its center ofgravity, so that it also tends to fall away from the poles of themagnet. Said armature carries a short stud 0 adapted upon the attractionof the armature to engage the indicatorlever between its pivotal supportand the indicator to force the indicator to its upper or concealedposition. The indicator is covered when it lies in its, upper positionby a plate i, but when in its lower position lies before an opening 7)in the plate. The armature c is pro vided with a back contact 0 againstwhich it bears whenin its unattracted position. Thus when the magnet cis excited its armature is attracted, breaking contact with its anviland engaging the lever-arm to restore the indicator to its concealedposition.

The visual-signal device shown forms no part of the present invention,but constitutes the subject-matter of my application filed July 11,1902, Serial No. 115,131, of which this application is a division.

The operation of the system may be briefly outlined as follows: Whilethe apparatus is ,station A desires connection with the subscriber atstation C, he first removes his tele phone from its hook, therebycompleting a circuit from the central-ofiice battery B, branch conductor3, through the winding of magnet b of the line-signal device I), overlimb 1 of the line to the subscriber, returning over limb 2 of the line,through ground branch 4, including the armature c and back contact 0 ofsignal-restoring magnet c. The magnet 6 thus becomes energized andattracts its armature b thereby relieving the indicator-arm of itsoverbalancing-weight, whereupon said arm moves downwardly into aposition to display the target (1 before the opening in the plate i. Theoperator upon observing the signal inserts her answeringplug 0 intoanswering-jack a of the line and operates her listening-key in the usualway, inquiring the number of the subscriber with whom connection isdesired. The closure of the connection-switch a 6 applies current fromthe battery B, associated with the link conductors, to the line, whichcurrent flows from the positive pole of said battery B through theindicator-displaying magnet b of the supervisory signal to the linkconductor 5, through contacts a e of the connection-switch, to the limb1 of the line, through the indicator-restoring magnet c of thelinesignal to the substation, returning over limb 2 of the line throughthe alternative contacts a e of the connection-switch, link conductor 6,branch 8, through the signal-restoring magnet of the supervisorysignaldevice 9 to the ngative pole of the battery. The magnet c of theline-signal device now being energized attracts its armature c, whichengages the indicator-lever and moves the same to withdraw theindicator, at the same time opening the ground branch from the limb 2 ofthe line to remove the ground connection from the test-piece a of thespring-jack a, a test-potential being created at the thimbles of thejacks by current from battery B. The supervisory-signal device 9 wouldnot, of course, be operated, since current from battery B is traversingboth of its magnets b 0, its operation, however, being under the control of the substationswitch, which controls the restoring-magnet 0thereof. A circuit from battery B is now completed through both magnetsof the line-signal, contacts a e of the spring-jack a, and plug 6through the indicator-displaying magnet b of the supervisory signal 9 toearth, the circuit being independent of the telephone-switch at stationA.

Assuming that the subscriber with whom,

ICC

multiple jack of the line to station C, whereupon a circuit is completedfrom the linebattery' B, associated with the called line through themagnet I) of the line-signal device thereof to limb 1 of the line,thence through the indicator-restoring magnet c of the line-signal,through contacts of the calling-plug and multiple jack to strand 5 ofthe cord-circuit, and thence through the indi cater-displaying magnet ofthe supervisory signal h to earth. Said magnet thereuponbecomesenergized and efl'ects the display of the target of saidsupervisory signal; but the line-signal of the called line remainsinert, since both of its maonets are simultaneously energized. Theoperator now of course applies the usual ringing-current to the calledline to operate the bell at the substation B.

When subscriber at station C removes his telephone from its book, acircuit is co m pleted from battery B to the called station, includingboth the magnetsof the supervisory signal it similar to the circuittraced with relation to the calling-line, whereupon the indicator iswithdrawn.

It will be apparent that the movement of the telephone-switches willcontrol the corresponding supervisory signals, either signal beingdisplayed when the telephone at the station to which it refers is placedon the switch-hook. Neither of the line-signals, however, is displayedafter connection has been established.

When the subscribers hang up their telephone-receivers at thetermination of the convcrsation, the circuits from battery B, includingthe restoring and displaying magnets of both supervisory signals 9 h,are broken but the grounded circuits from battery B, including theindicator-displaying magnets of the said supervisory signals 9 it,remain completed, whereupon the indicators of both signals aredisplayed. The operator upon withdrawing the plugs e e restores theapparatus to its normal condition, the armatures of theindicator-displaying magnets in retracting overbalancing the indicatorleverarms and withdrawing the indicators.

It will be observed that while the apparatus is in its idle or inertcondition the testrings of the multiple jacks are reduced to thepotential of the earth, the line conductor 2, with which they areconnected, being grounded through the switch-contacts c of thelinesignals of the respective lines. \Vhen connection is made with anyline, however, the battery B becomes connected with these test-rings,while at the same time the earth branch from the line conductor 2 isbroken. Thereafter the test-rings are electrified to a considerablepotential above the earth, so that they will test busy at the othersections of the multiple switchboard in the usual way.

I claim- 1. The combination with a metalliecir cuit line, and means forclosing the line at the substation, of a line-signal indicator and acontrolling-magnct there'l'or in a permanent ground branch from one ofthe line conductors, a ground branch'lrom the other line conductor, amagnet adapted to eflace the indicator when displayed, andswitch-contacts actuated by said last-mentioned magnet for breaking saidground branch, and means for exciting the said last-mentioned magnet inmaking connection with the line, as described.

2. In combination with a metallic-circuit line and means for closing theline at the sub station, of spring-jacks in a multiple switchboard iorthe line, the test-rings of the springjacks being connected with one ofthe line conductors, a ground branch from said line conductor, a signalcontrolling magnet in a permanent ground branch containing a bat tcryfrom the other line conductor, a magnet adapted to restore the signal,and means for exciting the said last-mentioned magnet in makingconnection with the line, and switchcontacts operated by saidlast-mentioned magnet for breaking the ground branch from thetest-rings, as described.

The con'ibination with a telephone-line and a spring-jack thereof, and aplug and plug-circuit therefor, of a line-signal-con trolling magnet ina ground branch from the line including a battery, a magnet adapted toel'l'ace the indicator of said signal when displayed, saidlast-mentioned magnet being serially included in the line between thebranch and the spring-jack, and a ground branch from the conductor olthe plug circuit which is connected with said serial magnet, asdescribed. 1

4. The combination with a metallic-circuit line and a switch at thestation for closing the circuit, a spring-jack for the line and a plugand plug-circuit for making connection therewith, of the line-signal ina ground branch from one of the line conductors together with a battery,a ground branch from the other line conductor, an indicator-rcstoringmagnet for resetting said line-signal serially included in the linebetween the spring-jack and the ground branch, said indicator-restoringmagnet being adapted to break the ground branch connected with the otherconductor of the line, and a bridge of the cord-circuit containing abattery, as described.

5. In a supervisory system for telephonelines having telephone-switchesfor closing the lines, a supervisory signal associated with the plugcomprising a pivoted weighted indicator, an overbalancing-armature and amagnet therefor, and a restoring-armature and a magnet therefor adaptedto conceal said indicator, of a circuit independent of the telephoneswitch containing the magnet of said overbalancing-armature, and aswitch ICC for closing said circuit and acircuit including saidrestoring-magnet, said last-mentioned circuit being controlled by thetelephoneswitch, as described.

6. In combination with a telephone-line and a telephone-switch at thestation thereof, a spring-j ack for the line, and a plug andplugcircuit, a supervisory signal having an indicator, and means fordisplaying it, an armature engaging said indicator to counteract saidmeans, and a magnet for said armature, a circuit for said magnet closedin registering contacts of the spring-jack and plug, and independent ofthe telephone-switch, a restoring-armature adapted to counteract saidmeans to conceal the indicator, and a magnet therefor, saidlLStfln611tlO118d ,magnet being in a circuit of the line controlled bythe telephone-switch, as desired.

7. The combination with a telephone-line extending from a substation toa central office, of a source of current at the central office, of atelephone-switch at the substation controlling said circuit, avisual-signal device for the line at the central oflice, a magnet, anarmature therefor normally overbalancing the indicator of the signaldevice to conceal the same, said armature when attracted being adaptedto display the indicator said magnet being controlled by the substation.telephone-switch, link conductors at the central oflice, aconnection-switch for uniting said link conductors with the line, amagnet adapted to withdraw the indicator of said signal device, and acircuit for said magnet completed upon the closure or saidconnection-switch.

8. The combination with a telephone-line extending from a substation toa central office, of a source of current at the central office, of atelephone-switch at the substation controlling said circuit, avisual-signal device for the line at the central oflice, a magnetadapted to display the indicator of said signal device, a circuitcontrolled by the substation telephone-switch, link conductors at thecentral oflice, a connection-switch for uniting said link conductorswith the line, a magnet adapted to withdraw the indicator of said signaldevice, a circuit for said magnet completed upon the closure of saidconnection-switch, a supervisory visual signal associated with theplug-circuit, an indicatordisplaying magnet there-for included in saidlastmentioned circuit, and a restoring-magnet for said supervisorysignal in a circuit controlled after the closure of saidconnectionswitch by the substation-switch; whereby the indication of theline-signal is eflaced and the indicator of the supervisory signal ismade responsive to the telephone-switch upon the closure of saidconnectionswitch.

9. In a supervisory system, the combination with a telephone-line and atelephoneswitch at the station thereof, a spring-jack for the line and aplug and plug-circuit, of a signal-controlling magnet in a ground branchfrom the line with a source of current, a signal-restoring magnetserially in the line between said branch and the spring-jack, a groundbranch from the other line conductor, said last-mentioned branch beingcontrolled by the restoring-magnet, a su ervisory visual signalassociated with the p rig-circuit, an indicator-displaying magnetthereof in a ground branch from said side of the line containing thesignal-restoring magnet, a restorlug-magnet of the supervisory signal ina ground branch from the other side of the plug-circuit, saidlast-mentioned branch containing the source of current whereby theindication of the line-signal is effaced and the indicator of thesupervisory signal is made responsive to the telephone-switch to bedisplayed when the switch opens the linecircuit, as described.

10. The combination with a telephoneline extending from a substation toa central source of current and a telephone-switch at the substationcontrolling said circuit, of a visual-signal device for the line at thecentral oflice comprising a pivoted weighted indicator, anoverbalaiicingarmature therefor, a magnet controlling said armatureresponsive to said substation-switch, a restoring magnet and armaturefor said indicator, link conductors at the central oflice, aconnectionswitch for uniting said link conductors with the line, and acircuit for said restoring-magnet completed upon the closure of saidconnection-switch.

In witness whereof I hereunto subscribe my name this 27th day 'ofDecember, A. D.

FRANK R. MOBERTY. Witnesses:

W. S. DUNCAN, E. F. BEAUBIEN.

